Field
Embodiments of the application pertain generally to cell incubators, microarrays, microfluidic systems, and miniature biochemical and chemical detectors, and more specifically to microprocessor-controlled microfluidic platform technologies comprising such miniature biochemical and chemical detectors configured as instrumented cell incubators for providing a plurality of simultaneous distinct controlled micro-environments for living cell cultures.
General Background
Culturing cells, such as tissue cells, cancer cells, bacteria, yeasts, molds, plankton, infectious protozoa, etc. as well as cell-related materials such as infectious viruses and prions in the laboratory typically require managed, and often precisely managed, environmental control. In the laboratory, cell incubators are the most common and essential equipment for nurturing and maintaining living cells.
Cell incubators typically provide several environment-providing functions that often must meet or operate within numerous rigid specifications relating to temperature, humidification, gaseous environment, sterilization, and specimen safety. Additionally these conditions are not uniform across cell types. For example, culturing mammalian cells and bacteria require the temperature at 37° C., 5% carbon dioxide, and 95% humidity and sterilized condition. However, other cell types, for instance the budding yeast Saccharomyces cerevisiae grows at a temperature at 30° C.
Contemporary cell incubator technologies can provide computer controlled thermal regulation, humidified control, control of gas levels such as CO2, O2, and N2, and illumination of cell cultures contained in open (or in some cases closed) dishes and welled microplates. In addition, many contemporary cell incubators can be programmed to control environmental factors through a sequence or cycle of distinct temperatures, humidity levels, etc.
In vitro study can involve study of biochemical process or pharmacodynamical substances provided to cultured cells. Examples include adding pharmaceuticals and changing aspects of the culture medium. In order to enact these, the sample must typically be removed and translocated to outside the incubator, thus discontinuing or disrupting the controlled cell nurturing condition. In contrast to in vitro study, in vivo study provides a consistent biological environment for observing biological responses from the effects of medical treatment. Uninterrupted controlling of the conditional environment while studying cellular responses can minimize the introduction of corrupting processes and far more precisely mimic the actual biological environment of the body of a higher organism or other natural cellular environment.
In addition, the required and optimal conditions of the biological environment for various cell types are often different, especially in regards to the proportion of ambient gases such as carbon dioxide (CO2), oxygen (O2) and nitrogen (N2). For example, cells within a solid tumor malignancy are in hypoxia (low oxygen), yet normal cell is in normoxia (normal oxygen). Additionally, hypoxia conditions play an important role in gene expression related to cellular signal transduction. Therefore, to study the cellular responses at the desired cell culture conditions—hypoxia and normoxia, control of the proportion of gases during cell incubating is considered.
To study effects of substance concentrations on the biological responses, monitoring levels of the interested substances are concerned. For example, different concentrations of nitric oxide (NO) are relevant to cell signaling and cell apoptosis, measuring concentration of nitric oxide at steady states is required during cell culture. In some cases, substances of interest are produced naturally by biological process, while in other types of experiments, substances of interest are introduced artificially.
Further, it is noted for example that due to its highly reactive nature, artificially provided NO typically must be introduced very locally to NO affectation/consumption regions by controlled introduction of NO-donor compounds. Other types of substance concentration experiments can require highly localized substance measurement (for example by means of substance-responsive fluorescent markers) and/or highly localized substance introduction (for example by means of substance-generative donors)
To study the pharmacological and biochemical effects via in vitro study, observing cell responses from within incubation—i.e., without removal and interruption of the period of environmental control, would be expected to provide higher accuracy and diminish corruption opportunities. However, current methods for determining the effects of the substances on the cells involve waiting until cells are stable in the cell culture medium and environment and subsequently performing an operation outside the environmental control provided by the incubator. Even though efforts can be taken to minimize analysis time outside the incubator can reduce corruptive effects, often cells are still very sensitive to changes of environment. In addition, other aspects of cell response study can be affected and made more complicated. Therefore, processes such as treating the cells with substances and analyzing the cell responses against monitored desirable conditions, and operations of processes within the control condition in the incubator have become a formidable challenge for in vitro studies.